1. Field of the Invention
This invention relates to 3,4-dihydrocarbostyril derivatives and a process for preparing the same. More particularly, this invention relates to 3,4-dihydrocarbostyril derivatives represented by the formula (I) hereinafter described, the pharmaceutically acceptable acid addition salts thereof, and a process for preparing the 3,4-dihydrocarbostyril derivatives of the formula (I).
2. Description of the Prior Art
It is well known that certain carbostyril derivatives exhibit useful pharmaceutical activities. Representative compounds of this type have been disclosed in Journal of Medical Chemistry, Vol. 15, No. 3, pp 260-266 (1972), Japanese Patent Publication No. 38789/1971 and Chemical Abstracts, 62, 16212e (1965), etc. However, these prior art references do not teach that the compounds having a wide variety of substituted-amino groups at the 6-, 7- or 8-position of the 3,4-dihydrocarbostyril moiety possess an excellent .beta.-adrenoreceptor blocking activity.
Hitherto, various carbostyril compounds have been disclosed as having a .beta.-adrenoreceptor blocking activity. For example, U.S. Pat. Nos. 3,340,266, 3,910,924 and 3,953,456, and German Patent Application DT 2,549,889 disclose that 3,4-dihydrocarbostyril derivatives having a (2-hydroxy-3-substituted-amino)propoxy group at the 5-, 6-, 7- or 8-position of the 3,4-dihydrocarbostyril nucleus possess a .beta.-adrenoreceptor blocking activity, i.e., .beta.-blockers. Also, Japanese Patent Application Laid Open to Public Inspection Nos. 48676/1976 (published on Apr. 26, 1976) and 52177/1976 (published on May 8, 1976) disclose 3,4-dihydrocarbostyril compounds having a (2-hydroxy-3-substituted-amino)propoxy group at the 5-position and a nitro group, an acetamido group or an amino group at the 8-position useful as .beta.-blockers.
However, these .beta.-blockers are usually contraindication to subject suffering from bronchial asthma and, therefore, it has been desired to develope .beta.-blockers having a high cardioselectivity.
Recently, carbostyril compounds having a (2-hydroxy-3-substituted-amino)propoxy group at the 5-position of the carbostyril or 3,4-dihydrocarbostyril nucleus were found to have a cardioselective .beta.-adrenoreceptor blocking activity, as disclosed in German Patent Application No. DT 2,615,406 and U.S. application Ser. No. 778,539 filed on Mar. 17, 1977 (German Patent Application No. P27 11 719.7 filed on Mar. 17, 1977). Such cardioselective .beta.-blockers would be very useful for treatment of carbiac disorders such as angina pectoris, heart arrhythmia and hypertension. The compounds of the present invention were also found to have excellent cardioselectivity better than that of these known compounds and are useful in treatment or prophylaxis of cardiac disorders in subjects suffering also from chronic obstructive lung disease such as bronchial asthma.